Just an idea for a mulch that is pretty to use on the less succulent foliage plants. I like to use a sphagnum moss or orchid moss. It hides the soil, absorbs some of the moisture and you can easily roll it back to check the moisture level in your plant soil.

I suspect your plants will quickly fill in so they won't even need a surface mulch.

Have you throught about taking your beautiful terra cota pots and setting the smaller plants in them? Either in singles or multiples and then covering the surface with a light mulch.

We will look forward to seeing photos of your lush "jungle" when finished.

Be content moving inch by inch because, by days end, the inches, will add up to feet and yards.

Thank you so much for your suggestions @pod! I would love to try the sphagnum idea! Yes, I have been filling the bigger ones with some of the smaller, but the problem is that when doing so, the surface of the soil that the big, "main" plant is in, stays moist for ever under the smaller pots, even if they are for example little nursery pots with succulents. So, that is nice for some of the plants that love moisture, but not to the ones that hate it! The sphagnum would solve this, as it would absorb moisture instead retaining it into the soil.

In some Native languages the term for plants translates to "those who take care of us."
Robin Wall Kimmerer